BIO 286 Definition Flashcards

Definitions from intro to ecology & evolution

Proximate causes

the mechanism/direct effects of external stimuli

Ultimate causes

the why/factors that led to the appearance of certain traits

Microevolution

changes in allele frequencies within a population over time; short term. Populations evolve

Macroevolution

evolution of great phenotypic change that creates a distinct genus

Natural selection

differential survival/reproduction of entities that are different

Artificial selection

selection driven by human selection

Adaptation

traits that provide enhanced survival/reproductive success in a given environment, relative to individuals who do not possess that trait

Fitness

genetic contribution of individual to successive generations (is relative)

Heritability

Proportion of variance among individuals in a trait that is attributable to differences in variance

Phenotypic plasticity

ability of a single genotype to exhibiit different phenotypes in different environmental conditions

Polyphenic traits

traits where multiple phenotypes arise from 1 genotype due to different environments

Mutation

Changes in DNA sequence

Horizontal gene transfer

genes from 1 species introduced into another organism

Directional selection pattern

One extreme of a phenotype is favored

Stabilizing selection pattern

The intermediate/middle phenotype is favored

Disruptive selection pattern

Both extremes of a phenotype are favored

Frequency dependent selection pattern

where the fitness of a pheno/genotype varies with its frequency in the population, can lead to oscillations in frequency

Genetic drift

random changes in allele frequency

Gene flow

Net gain/loss of alleles by movement of individuals in/out of population

Duplication mutation

A repeat of all/segment of a chromosome in one DNA strand

Inversion mutation

removal and reinsertion of inverted DNA

Epigenetics

processes that change gene expression without change in sequence of DNA

Histone acetylation

histone protein tails less positively charged, less tight & easier transcription

DNA methylation

addition of methyl groups to cytosome, decreases transcription

Outcrossing

offspring from distinct individuals

Haplotype

Closely linked loci on chromosome resulting in nonrandom associations between alleles at one locus and those at another, protected from recombination

Linkage disequilibrium

regions of chromosomes with lower rates of recombination than expected from chance

Modern Synthesis

Mathematical models and genetics to test evolution; from 1930s-40s

Population genetics

study of heritable features of a population over time/space

Hardy-Weinburg Theorem

Serves as a null hypothesis for whether microevolution is occurring in a population. Assumes large pop size, random mating, no gene flow, all genotypes with equal fitness, and no mutations.

Phenotypic quantitative traits

traits with continuous variation, is the result of alleles at many loci interacting with environment

Absolute fitness

survivorship of each genotype (# of individuals)

Relative fitness

ability of 1 genotype to survive relative to others

Inbreeding

Mating among related individuals that results in increased homozygosity

Population bottleneck

Where a population is lost/prevented from breeding over a short period of time, followed by a rebound

Behaviors

internally coordinated responses of organisms to internal/external stimuli, evolve and are a phenotypic trait

Parasperm

sperm without nuclei that can’t fertilize egg but can block other sperm from reaching the egg

Kamikaze sperm

Attacks and destroys other sperm

Stimulus response behavior

Behavior that occurs as a result of an external stimuli

Sexual dimorphism

difference in external appearance, physiology, behavior, immunology, etc. between 2 sexes of a species

Sexual selection

form of natural selection where individuals within 1 sex secure mates at the expense of other individuals within the same sex

Bateman’s Principle

If males experience greater variation in reproductive success than females because more of their sperm will not fertilize an egg, males will experience greater opportunity for sexual selection

Balance Hypothesis

If male traits show greater degree of dimorphism, it can be exaggerated by female choice until overall fitness cost of dimorphism trait is too high

Truth in Advertising Hypothesis

elaborate phenotypic traits are indicator of male fitness

Mating systems

A set of relationships between females and males during reproduction, including contribution to parental care, number of mates, and length of relationship

Monogamy

male mates with single female during reproductive lifetime

Serial monogamy

Monogamy lasts for a single breeding season

Polygamy

individual may have multiple reproductive partners

Polygyny

Male mates with multiple females

Polyandry

Female mates with multiple males

Extra pair copulations

happens in monogamous species, is mating with individuals other than a social mate for either increased mating success (males) or increased genetic variation of offspring (females)

Altricial offspring

incapable of independent movement, may require biparental care

Precocial offspring

born relatively well developed, may not require biparental care

Lek Mating

Where males display together on sites known as leks, and females choose mates based on displays

Harems

a group of females that a male defends from other males and has exclusive reproductive access to

Positive assortative mating

mating between individuals of similar phenotypes

Negative assortative mating

mating between opposite phenotypes

Autogamy

self fertilization, likely inbreeding depression

Apomixis

asexual seed formation without meiosis and fertilization, no genetic variation

Social systems

interactions within and between social units

Cooperative breeding

social system where group members help raise young they didn’t produce, while potentially delaying their own reproduction

Kin selection

A form of natural selection where genes/phenotypes can be favored if they contribute to indirect fitness

Direct fitness

personal reproductive success

Inclusive fitness

success of individuals that carry copies of one’s genes

Social reciprocity

mutual exchange of goods/actions for the benefit of each member in the exchange

Phylogeny

Evolutionary tree that shows history of divergence and change from ancestor to descendants

Homologous characters

those that are similar among different organisms due to being derived from common ancestor

Analogous characters

traits that serve a similar function but differ in evolutionary origins, and are a result of convergent evolution

Convergent evolution

Similarities between species in certain traits caused by similar but evolutionarily independent responses to common environmental problems

Homoplasy

development of structures/organs/traits in different species without common ancestral origin

Parallel evolution

similar phenotypes that arise from similar developmental origins in different species

Allopatric speciation

occurs in populations with discontinuous distributions

Dispersal speciation

Type of allopatric speciation where new pop established in area with unique selective pressures

Peripatric speciation

Type of allopatric speciation where small isolated pop drifts to become reproductively isolated

Vicariance speciation

Type of allopatric speciation where existing pop are divided by physical barriers

Sympatric speciation

occurs among populations with overlapping distributions; reproductive isolation

Polyploidy

changes in chromosome #, can also result in speciation

Species

No formal definition, but some: groups of interbreeding organisms with isolated gene pool

Subspecies

group of phenotypically similar populations of a species inhabiting a geographical subdivision of the range of that species but differing taxonomically from other populations of that species

Microsatellites

tandemly repeated DNA motifs of various lengths

Genetic haplotypes

Combinations of gene variants, usually single nucleotide polymorphisms (SNPs) likely to be inherited together

Coalescence

Tool to characterize evolutionary relationships and effective population sizes. Assumes genetic drift as null and generates gene evolutionary trees as hypothesized relationships

Ecotypes

genetically distinct populations adapted to local conditions that may be on route to speciation

Adaptive radiation

rapid speciation; organisms that rapidly and simultaneously diversity from a common ancestor

Introgression

Allows alleles from 1 species to be incorporated into the gene pool of another

Life History

pattern of how organisms allocate time and energy among various activities throughout life that affect survival, maturation, and reproduction

Life history strategies

suite of life history traits of an organism that have evolved through natural selection

Life cycles

sequence of developmental stages of an organism from gamete to death, can be simple or complex

Complex life cycle

change in body plan occurs at some point; metamorphosis

Neoteny

development of sexual larval forms that no longer metamorphose into adults

Resting stages

developmental stage where organism is dormant/inactive and resistant to harsh conditions

Iteoparous

reproduce multiple times during life

Semelparous

reproduce only once, and produce many offspring at once

Filial infanticide

Parents kill their own offspring due to lack of resources/too weak offspring

Fatal starvation

parents limiting food access to a particular offspring

Sex determination

factors that influence sexual characteristics of an organism and the hormones associated with reproductive development

Hermaphrodites

contain both female and male reproductive structures in lifetime

Sequential hermaphrodites

Change sex at some point to maximize lifetime fitness

Protandry

Initially male, become female

Protogyny

initially female, become male